High CPU usage when streaming a file

[maxmil]

Hi,

 

I have a web application that allows users to download pdf files from the server. To control access to these files they are not in a directory that is visible from the web. When a user requests one of the files the code sets the necessary headers and writes the files bytes to the output. Using

fpassthru($file);
flush();

 

The problem is that when this occurs there is a peak in the CPU usage of the server which can (momentarily) go as far up as 100%.

 

I have tried other methods of streaming the file such as

while(!feof($file)) {
   print(fread($file, 1024*);
   flush();
}

 

But the result is the same.

 

How can i control these peaks in the CPU usage? Any comments welcome.

 

max